1. Field of the Invention
The invention relates to a testing equipment for fire alarms comprising a testing pole, a range spacer connected to the testing pole, and a reflection means and scattering means situated in the inside of the essentially pot-shaped designed range spacer.
2. Description of Related Art
Fire alarms have to be tested at periodic intervals for their operability. In Germany, for example, every fire alarm has to be tested at least once per annum according to Regulation VDE 0833.
A so-called stray light fire alarm usually includes a radiation emitter and a radiation receptor which are situated in such a way that no radiation is able to reach the radiation receptor directly from the radiation emitter. Radiation emitters and radiation receptors are rather situated in such a way that the radiation cone, that starts from the radiation emitter, and the space region, in which the radiation receptor reacts sensitively to the radiation, intersect. If smoke particles get into this intersection region that is also known as a scattering volume, the radiation coming from the radiation emitter is scattered by the smoke particles, and a part of the scattered radiation thus reaches the radiation receptor. The quantity of scattered radiation that reaches the radiation receptor at a given brightness of the radiation emitter depends on the nature of the smoke (smoke particle size, color of the smoke), the wavelength of the radiation used and the angle of scattering (the angle between the optical axis of the radiation emitter and the optical axis of the radiation receptor). The radiation emitter is usually controlled by a microcontroller. The radiation receptor is connected to amplifying electronics. The amplified scattered light signal is able to be read in by a microcontroller via an A/D converter and evaluated. If the scattered light signal exceeds a certain threshold, the fire alarm is triggered. This alarm is passed along via a bus system to a fire alarm center, from where the fire fighters are then alarmed. In order to exclude interference in the measuring device by ambient light, in current fire alarms, radiation emitters and receivers are surrounded by a cover which does let smoke particles through, but excludes light. Because of the shape of such covers, they are called a “labyrinth” in everyday conversation. The sensitivity of such scattered light measuring devices is great, so that, with respect to the labyrinth covers, one has to take care that no stray light impinges upon the receiver, by reflection from the chamber walls. The constructive formation of such covers is correspondingly complex. The smoke entry openings of labyrinths are usually provided with a screen, so as to prevent insects from penetrating into the measuring chamber and causing interference signals. In current scattered light fire alarms, the operability of the scattered light sensor is checked by generating artificial smoke to which the fire alarm then responds with an alarm. Artificial smoke is usually generated by atomizing a substance in an atomizer into very small droplets (aerosol), which act on the fire alarm like smoke. What is disadvantageous in this method is that, after the testing, the aerosol frequently does not disappear completely without leaving a residue, but rather deposits as a film on the fire alarm housing or in the fire alarm itself. In connection with dust, this can then lead to an undesirable dirtying of the fire alarm which impairs its operating safety. A further disadvantage of this testing method is that the concentration of the test aerosol is controllable only with great difficulty. Therefore, in general, such a high concentration of test aerosol is liberated that the fire alarm emits an alarm with certainty, inasmuch as it is still operable at all. Therefore, using this method, it is not possible to measure somewhat exactly the sensitivity to making a response. This frequently leads to the result that fire alarms which are just still operable, but which, based on aging effects or as a result of pollution have a response sensitivity that is much too low, are not recognized as being faulty. In case of a fire, however, an alarm is triggered by these fire alarms much too late, since they do not respond in time to a low smoke gas concentration. Fire alarms are also known in which several sensor principles are combined. In an optic-thermal fire alarm, the detection of the combustion gas is combined with a temperature measurement in order to detect a fire. In addition, gas sensors that detect fire gases may be installed in a fire alarm, and combined with the smoke sensor and/or temperature sensor. In the case of a combined fire alarm, the operability of each individual sensor has to be checked. This may be done by testing the individual sensors one after the other, this having the disadvantage that in this method the testing time and therewith the testing expenditure greatly increase with the number of individual sensors to be tested. However, besides the acquisition costs, the testing and the maintenance expenditures are important criteria in selecting a certain type of fire alarm. This has the disadvantageous result that the greater part of installed fire alarms are equipped with only one sensor, although fire alarms equipped with several sensors give better performance, and particularly have a lower rate of false alarms.
Another possibility of testing combined fire alarms is to use a testing unit in which all the sensors that are contained in the fire alarm are addressed at the same time. Such testing units are known from US 20902/0021224 A1 or DE 100 47 194 C1.